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7/29/2019 InTech-Wick Debinding an Effective Way of Solving Problems in the Debinding Process of Powder Injection Molding
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4
Wick Debinding – An Effective Way of SolvingProblems in the Debinding Process
of Powder Injection Molding
Lovro Gorjan Jožef Stefan Institute,
Research and Development Center for Ignition Systems and Electronics d.o.o.,Slovenia
1. Introduction
Powder injection molding (PIM) has been shown itself to be a successful shaping techniquefor producing complex-shaped ceramic, metal or cermet parts. The process starts withpreparing a high solid loading suspension, where ceramic or metal powder is mixed with a
thermoplastic material. At high temperature the suspension is fluid and can be injected intomolds by applying a pressure. Inside the mold the suspension takes the shape of the moldand then cools below the melting point of the thermoplastic material and solidifies into agreen body. After the molding cycle the green body consists of solid particles held togetherby the thermoplasic phase, which serves as a binder.
The challenging and time-consuming operation in the powder-injection molding process isremoving the binder from the green bodies prior to the sintering, without causing anydeformation or cracks. The debinding process is difficult because green bodies containrelatively large amount of poorly volatile binder in the solid state, i.e. below the melting point.Debinding is usually achieved by slowly heating the green bodies, causing the binder todecompose and vaporize. This is the thermal debinding process. The difficulties are especiallysevere in low-pressure injection molding, since in this case the binder does not contain abackbone polymer that would hold the particles firmly in place during the debinding. Low-pressure injection molding (LPIM) is a variant of injection molding where relatively lowpressures are used, typically less than 0.7 MPa, and the pressure is applied using compressed
air instead of a screw (like in the more common high-pressure variant). The liquid medium inthe feedstock is a low-melting-point wax, which is crucial for the low viscosity of the moltenfeedstock. The advantages of LPIM, in comparison with other ceramic injection techniques,include the lower cost of the molds, less die wear and less expensive and simpler equipmentfor the injection molding (Zorzi et al., 2003; Cetinel et al., 2010; Loebbecke et al., 2009; Gorjan etal., 2010). The method has also been shown to be appropriate for the shaping ofmicrocomponents (Cetinel et al., 2010; Bauer & Knitter, 2002; Wang et al., 2008).
However, an effective way of reducing the formation of defects in the process of binderremoval exists. That is, to introduce an additional debinding step – debinding in a wickingembedment (Curry, 1975; German, 1987; Wei, 1989; Liu, 1999; Bao & Evans, 1991; German,
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Some Critical Issues for Injection Molding90
1990) or wick-debinding. A wicking agent can be in the form of a porous solid substrateplate or in the form of a loose powder or granulate. The granular form offers a gentlephysical support for samples, regardless of their shape, and thus prevents certain flaws,such as distortion and cracking. The capillary extraction is uniform over the entire surface of
the green body, which ensures that debinded parts also have, as much as possible, a uniformstructure after the wick-debinding. A solid plate does not offer so many benefits; however ithas one advantage over the granular form of wicking agent, i.e., there are fewer practicalproblems when handling the compacts after the debinding. The wick-debinded parts do nothave to be cleaned and are simply transferred to the sintering furnace.
Fig. 1. Wick-debinding on a porous plate. The molten binder is extracted from the greenbody into the porous supporting plate.
Fig. 2. Wick-debinding in a embedment of porous powder or granulate. The molten binderis extracted in all directions from the green body.
The wicking embedment can be utilized with great success in either the high- or the low-
pressure injection molding. However, its use is more beneficial in the low-pressure variant,where the debinding is a more delicate operation.
2. Fundamentals
The basic principle of wick-debinding is the phenomenon called capillarity, which is a
spontaneous flow of liquid into small pores. This effect occurs because of the attractiveforces between the liquid and the solid surface of the pores and the surface tension of the
liquid. The attraction of the liquid to the surface causes the adhesion of the liquid and the
solid, which results in the liquid wetting the surface. The wetting is characterized by awetting angle, which depends on the interactions between the liquid phase, the solid phase
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Wick Debinding – An Effective Wayof Solving Problems in the Debinding Process of Powder Injection Molding 91
and the atmosphere. The smaller the wetting angle the better is the wetting and the liquideasily spreads over the surface.
Fig. 3. Sketch of a droplet of liquid on a solid surface showcasing the wetting phenomenon,characterized by the wetting angle (Φ). When a liquid wets a surface it spreads over it.
An interesting phenomenon occurs when the liquid is inside a small pore. When the liquidwets the surface of a small pore at a certain angle (Φ), the surface becomes concavely curvedas is sketched in Fig 4. Any curved liquid surface causes a pressure difference across theinterface (ΔPc = PV - PL) between the liquid and the surrounding atmosphere.
Fig. 4. The liquid, that wets the surface, inside a small, cyllindrical pore forms a concavespherical surface that causes a pressure difference between the liquid phase.
The equilibrium pressure difference is described by the Laplace-Young equation:
1 2
1 1
c L V P P P
R R(1)
where ΔPc [Pa] is the pressure difference between the liquid phase and the air phase, γ [N/m] is the surface tension, and R1 and R2 are the principal radii of curvature. As thecapillary surface is concave towards the atmosphere, the liquid pressure is lower than thatof the atmosphere, possibly reaching negative values, which is called a tensile stress insidethe liquid (Bouzid et al., 2011).
In the case of a small, cylindrically shaped, pore channel the surface of the liquid issymmetrical and R1 = R2 = R . On small scales gravity is not strong enough to significantly
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Some Critical Issues for Injection Molding92
influence the shape of the liquid surface so the surface has a spherical shape. If the wettingangle is considered the curvature in the small, tube-shaped, pore channel can be reasonedfrom Fig. 4:
2cos
dR (2)
Combining equations (1) and (2) we obtain a correlation between the capillary pressure, thewetting angle and the pore diameter:
4 cos cP
d(3)
From equation 3 it is clear, that the capillary pressure is inversely proportional to the porediameter. Because the capillary pressure is larger for smaller pores, the liquid is forced to
move from the larger to the smaller pores. So in the equilibrium state the liquid would fillthe smallest pores of the system. The main idea of wick-debinding is to get a green body,heated to the temperature where the binder is molten, in contact with a material that hasfiner pores than the pores of the green body. Capillarity would then cause the binder tomove from the green body into the material in the contact.
The wetting angle must be quite small for practical use. If the surface is not wetted by the
liquid (Φ > 90°) then cos(Φ) has a negative value, which means that the capillary pressure
would be opposite and the liquid would not enter the porous media.
In any case, in a real system the porous media consist of pores of different sizes and shapes.Even for a green body made of packed monosized spherical particles there are voids of
different sizes and shapes. However, real powders are composed of particles that aredifferent in size and shape, which leads to an even more complex pore structure and a widersize distribution of pores. A labyrinth of interconnected voids is present in the green bodyand also in the wicking agent. Because of the complexity of real systems, the equation (3) isdifficult to use directly. However, in real systems it has been experimentally observed thatthe liquid enters a porous body with a front (Bao & Evans, 1991; Somasundram, 2008) and asingle value of characteristic capillary pressure at the front can be successfully used.
Another important thing to consider in the debinding is the kinetics of the process. It isimportant, from a practical point of view, that the process is reasonably fast. The kinetics ofwick-debinding, besides capillary pressure, also depends on the resistance to flow through
the porous media. Each individual channel has a certain resistance - a viscous drag thatlimits the velocity at which the liquid is flowing through.
The motion of liquid substances is generally described by the Navier-Stoker equations,which arise from applying Newton's second law to fluid motion. However, these equationsare too complicated for practical use in describing debinding phenomena since the shape ofthe liquid surface would present boundary conditions that are too complex. However, withthe development of computer software for liquid mechanics and because of the constantincrease in computer power it is possible that accurate simulations of debinding will bedeveloped in the future. Nevertheless, a simplified theoretical approach in dealing with thephenomena of debinding has produced satisfactory results.
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Wick Debinding – An Effective Wayof Solving Problems in the Debinding Process of Powder Injection Molding 93
The flow through an idealized single, long, circular, pore channel is described by the Hagen-
Poiseuille equation (4), which is also an exact solution of the Navier-Stokes equations with
certain assumptions, such as steady state, axisymmetric flow with no radial and swirl
components of velocity.
2
32
d Pq
L(4)
where q [m/s] is the flux or flow per area, ΔP [Pa] is the pressure difference between the
ends of the pore channel, μ [Pa s] is the viscosity and L [m] is the length of the pore channel.
The smaller the pore, the larger the viscous drag. This generally means that small pores
present a high resistance to flow. Again, like in the case of using equation (3), the Hagen-
Pouseille equation is due to the extremely complex shapes of pore channels in real systems,
inappropriate for calculations, but nevertheless it demonstrates that despite the high
capillary pressures, liquid transport through small pores can be slow. However, regardless
of the complexity of pore channels, the flow of a liquid through porous material can be
successfully described by a simple equation called the Darcy's law:
K Pq (5)
where q [m3/ (m2 s)] is the volumetric flux, K [m2] is the parameter called permeability, η [Pa
s] is the viscosity and P [Pa] is the pressure gradient.
The law was formulated in the 19th century by the French engineer Henry Darcy based on
the results of water flow through sand (Richardson & Harker, 2002). It is a constitutiveequation with a similar meaning for fluid flow as Ohm's law for the electricity and Fourier's
law for the conductive heat transfer. Darcy's law has been experimentally confirmed on
many different material combinations and is considered well proven. It has also been
derived from the Navier-Stokes equations.
The permeability (K ) is a characteristic parameter of a porous substance that depends on the
size, shape and interconnectedness of the individual pore channels and on the fractional
porosity. The complex shape of pore channels makes a permeability difficult to calculate or
predict from basic principles.
Many empirical equations have been used to determine the permeability from basicpowder-compact properties, such as particle diameter (d), specific surface (S) and fractionalporosity (E). Some of them are listed below (Bao & Evans, 1991; German, 1987):
3
225 1
EK
S E(6)
4 2
290 1
E dK
E(7)
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Some Critical Issues for Injection Molding94
2.422
190
EK
S(8)
These permeability correlations have been tuned for a forced flow through the porousmaterial, i.e. , the flow of liquid that is pushed through the material by applying an external
pressure. However, the permeability can be significantly different in the case of capillary
extraction, where the liquid is sucked out of green body by capillary forces.
The wicking agent must extract the liquefied binder from the green body, which is itself a
porous body. If the molten binder is removed from the green compact then a new surface
must be formed in the interior of that compact. This new surface, which initially appears in
larger pores, causes a capillary pressure in the opposite direction and resists extraction. A
competition for the binder emerges between the two porous media. Only the smaller pores
of the wicking agent might have a capillary suction that is strong enough to exceed the
capillary pressure of the green body. The liquid then travels into the wicking agent onlythrough these pores. In contrast, if the liquid were to be forced by the external pressure
through the wicking agent it would travel mostly through larger pores, which present a
smaller resistance.
The measured permeability, or that calculated from equations 6-8, could be significantly
higher than in the case of capillary extraction. This means, that conventional methods of
measuring permeability, such as measuring the forced gas flow through a sample of a
porous material, cannot be used to determine the permeability for the capillary-extraction
phenomenon. The mismatch between the forced flow and the capillary-extraction
permeability is especially large in the granular form of the wicking agent. A characteristic
case for porous material in the form of large granules with a fine porosity is schematicallypresented in Fig 5. If the fluid is forced through such a material the permeability would
appear much larger than if this granulate was extracting the liquid from another porous
material, for which a strong capillary pressure is required.
Fig. 5. In the capillary extraction the liquid flows only through smaller pores inside thegranulae, wheras in the case of liquid flow forced by external pressure the majority of flowwould be between the granulae.
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Wick Debinding – An Effective Wayof Solving Problems in the Debinding Process of Powder Injection Molding 95
Besides the kinetics of the capillary-extraction process it is crucial that the powder compact
of green body retains its shape after the process has been completed and no flaws are
introduced. One of the most critical moments in the process is the point when the binder
melts. At this stage the compact becomes quite weak and soft. This is especially critical in
the case of low-pressure injection molding, where only one component binder i.e., paraffinwax, is used. It is because of a characteristic known as the yield stress that the green body
retains its shape. The suspension behaves like a rigid body below the yield stress and flows
like a liquid above the yield stress. The yield stress is mostly governed by the particle size,
shape, solid content and the inter-particle forces.
However, a large yield stress is undesirable for the molding step, since it results in a low
moldability of the suspension (German, 1990). Suspensions with a high yield stress must
have high powder content, which also increases viscosity, which is again undesirable in the
molding step (German, 2003).
Fortunately, the yield stress of the molded green body can be significantly larger than theyield stress of the suspension before molding. This is because the particles rearrange during
molding and solidification into a denser configuration - a consequence of the shrinkage of
the binder after solidification. An increased attractive inter-particle interaction occurs in the
denser form (Dakskobler & Kosmač, 2009). Ideally the process does not reverse during re-
melting. If the inter-particle forces are high enough, then the particle arrangement will not
change; instead the expanding binder will be exuded from the body, while the particle
arrangement remains intact. A series of photographs of a LPIM sample, taken with an
optical microscope during heating from below to above the melting temperature of the
binder, is shown in Fig. 6.
A molten paraffin binder exudes out of the green body. This happens without anydisruption of the powder skeleton.
The extent of the exudation effect depends on the amount of low-melting point wax in thebody. During the melting the volume of the wax increases by 15%. The effect is mostpronounced in the low-pressure injection molding where the amount of wax is large –around 60 vol%. In high-pressure molding the amount of wax is around 10% – 30%.Thelarge amount of wax is an important factor that explains why in LPIM extreme difficultiesare encountered when a wicking agent is not used. In the HPIM process the yield strengthduring melting does not pose that big a problem, because the additional high-melting pointpolymer ensures that the particles are held in position. It has been shown that the yield
stress of molded parts can also increase with the storage time after the molding (Novak etal., 2000; Cetinel et al., 2010).
Water from a humid environment can penetrate the green body and interfere with the
bonds between surfactant molecules and the surface of the particles. The strength of the
inter-particle forces increases, which leads to a significant increase in the yield strength. This
effect can be made even faster, if the molded bodies are soaked in water (Novak et al., 2000).
Wicking embedment offers another benefit. It guarantiees a gentle physical support for the
parts. If the debinding takes place on a hard substrate there is danger that certain flaws will
occur, as schematically presented in the sketch in Fig. 7. The suspended parts of the green
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Some Critical Issues for Injection Molding96
Fig. 6. Exudation of the paraffin-wax binder during heating above the melting point of theparaffin, as observed with optical microscope. The photograph a) shows the state before themelting, b) shows the first molten paraffin exuding from the green body, c) shows thesituation 1 minute after the b) and d) shows state 10 min after the b).
Fig. 7. Green bodies with a complex shape can pose difficulties if they are debinded on asolid substrate. Small areas on which the green body rests on the substrate (1 and 2) can bedeformed due to the large compressive stress. Suspended parts of the body can bend due togravity or even crack at the point where the tensile stress is the highest (3). The wickingembedment can successfully reduce these flaws, since the support pressure is well spreadover the green body's surface.
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Wick Debinding – An Effective Wayof Solving Problems in the Debinding Process of Powder Injection Molding 97
body could bend or crack and point pressure areas where the green body rests on the solid
substrate can deform.
3. Overview of theoretical work
Because of the complexity of the capillary system in the porous green body and the wicking
agent the accurate and general theoretical model is difficult to obtain. Since the systems can
be quite different, the extraction can also show different behaviour. The existing theoretical
models predict different behaviors during the debinding and many even contradict each
other. The basis of all models is Darcy's law and some form of capillary-pressure
description. One of the first to theoretically describe the process of wick debinding for
injection-molded samples was German (German, 1987), who in 1987 proposed a model,
where he assumed that the binder is extracted from a molded compact as a continuous body
in liquid form, leaving behind a binder-free region.
A partially debinded compact should, therefore, have a characteristic binder distributionwith a binder-saturated region near the contact with the wicking powder and a region with
no binder on the other side. A sharp border between these regions should be present – a
sign of the trailing front of the molten binder. This model is simple and has frequently been
used as a basis for research in wick debinding. Monte-Carlo simulations of binder removal
based on German’s assumptions have also been conducted (Shih & Houring, 2001; Lin &
Houring, 2005). These simulations focused on binder penetration in the wicking embedment
and examined the case where pieces are not completely surrounded by the embedment.
However, German’s model has been criticized, on the basis of experimental data.
Contradicting this model, many researchers observed that the binder is uniformly
distributed inside the body at all stages of the debinding process (Liu, 1999; Bao & Evans,
1991; Vetter et al., 1994; Kim et al., 1999; Somasundram, 2008). There is also the question of
how the air can enter behind the trailing front into the binder-free region if the molded
pieces are completely surrounded by the wick (Somasundram, 2008). Furthermore, the
debinding rate does not correspond well with some experiments (Vetter et al., 1994). It has
also been observed that the permeability in a wick embedment can have important effects
and can be a limiting factor, rather than the flow through a sample, as was suggested in
German’s model [Vetter et al., 1994; Somasundram, 2008]. With more precise examinations
of the binder-removal rate it has been confirmed that wick-debinding must take place via
more than a single mechanism.
One clearly observable effect, for example, is a rapid decrease in the binder content at the
beginning of the process. This has been attributed to the pressure arising from the thermal
expansion of the binder [Somasundram, 2008, Gorjan et al., 2010]. Before the debinding
process, molded parts contain binder in the solid state, then during the melting a large, and
relatively sudden, expansion of the binder occurs. For example, the density of the paraffin
drops by around 15% during melting (Gorjan et al., 2010).
With further studies of the kinetics of capillary extraction it has been found that the molten
binder inside the body exists in different states, a differentiation based on the position inside
the body. It can behave as a 'mobile binder' located in the larger voids between the powder
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Some Critical Issues for Injection Molding98
particles, which can flow due to the pressure gradient caused by the wicking embedmentand as an 'immobile binder' located on the surfaces of the particles and inside the smaller
voids, which cannot be moved due to the capillary suction – it is too strongly bonded to thepowder and trapped inside smaller pores (Gorjan et al., 2010).
There can also be shrinkage during the debinding, which is inversely related to the ceramic
volume fraction, with less shrinkage in green bodies with a high solid loading. Very little or
no shrinkage occurs at a volume fraction of around 64% [Wright et al., 1990, Gorjan et al.,
2010]. In order to avoid a large shrinkage a green body must be made with high a green
density. A high green density is also beneficial for the sintering process; however, a high
solid loading is detrimental for the molding step. It is always necessary to make a certain
compromise.
Capillary extraction effectively removes only a part of the binder, because there is always acertain amount of the binder "trapped" inside the finest pores of the green body. This
residual binder must be removed in the form of a gaseous phase. In the case of oxideceramics the removal of the remaining binder can be achieved by controllably burning thebinder. If the temperature during wick-debinding is raised above approximately 200°C thenan organic binder starts to decompose due to oxidation reactions.
All of the binder can be removed if the temperature is increased above approximately 600°C,where even carbon burns. However, when all of the binder is removed from the body, thebody becomes extremely brittle and weak. In this state it would be impossible to remove itfrom the embedment and clean it without causing serious damage. One solution is to furtherheat the system to the temperature where first stage of sintering starts. Pre-sintered or'biscuit sintered' parts can then be safely removed from the embedment and since they
contain no binder they can also be sintered without problems. However, practical problemscan accompany this procedure. For example, if alumina parts are debinded a hightemperature is required for the pre-sintering and at this temperature the wicking agent alsostarts to lose the fine porosity and can stick strongly to the surface of ceramic parts.
Another, economically even more acceptable option is to heat the samples after the capillaryextraction to the temperature where the organic binder starts to decompose and then hold theparts at this temperature. It has been observed that at this temperature some amount ofparaffin wax cures into a hard, brown-colored, non-volatile resin, which remains in the partsand is stable at the dwell temperature of around 200°C. This curing effect drastically improvesthe strength of the samples, which increases with the dwell time (Gorjan et al., 2011).
Parts processed in this way can be made sufficiently strong for handling without any risk ofdamage. They are also appropriate for green machining, like cutting, boring and grinding.
Since they contain a very small amount of the binder, rapid heating inside the sinteringfurnace can be applied and the curing of the binder does not influence the strength of the
sintered ceramic parts.
A procedure of debinding, where the benefits of wick-debinding are fully used, has alsobeen developed, while the main drawback, i.e., additional cleaning and handling operationsare avoided. According to the patent the debinding and sintering can take place in a singlefurnace (Gorjan & Dakskobler, 2011). This can be achieved by using a high purity-carbongranulate, which completely burns after its role as the wicking agent is completed.
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Wick Debinding – An Effective Wayof Solving Problems in the Debinding Process of Powder Injection Molding 99
4. Practice
In a practical use the wick-debinding process can offer significant benefits. Faster and safer
debinding can be achieved in comparison with debinding a without the wicking agent. One
of the most important factors in the debinding practice is to avoid the introduction of defectsin green bodies. Potential defects include the loss of a compact's shape through distortion,
warping, cracking and also the undesirable strong adhesion of the wicking powder on the
surface of the debinded parts.
For example, in a low-pressure injection-molding, shaping technique it is almost impossible
to debind samples without using a wicking agent. In HPIM the use of wick-debinding can
be avoided, since the green body retains its strength after the wax has been melted due to
the presence of polymer, which binds the particles together. Also in the case of HPIM, the
wick-debinding reduces the possibility of flaws.
Fig. 8. Wick-debinding can significantly reduce the formation of flaws. Photograph a) showsthe low-pressure injection molded sample, debinded without wicking embedment, whilethe photograph b) shows the sample which was debinded in the embedment of highlyporous alumina wicking agent.
A major practical problem of wick debinding is the danger of causing defects when the parts
are removed from the wick embedment and cleaned afterwards. Because the debinded parts
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Some Critical Issues for Injection Molding100
can be quite fragile, a gentle and manually intensive operation is required. If the debinded
compacts are strong, then a more robust handling such as sieving can be applied. During
this handling the breaking of parts can occur.
In the practice a wicking embedment must also satisfy some additional considerationsbesides having good capillary-extraction characteristics. It is the most practical if it is in the
form of granules with a size of 50–200 μm. This size of granules ensures uniform contactwith a green body and has, at the same time, good flowability. This flowability is crucial for
easy handling. Smaller pores are powders tend to form dust, which is undesirable. Also, the
granules are easier to clean from the surfaces of the parts after the debinding process. Each
individual granule contains a very fine porosity, which is crucial for a highly efficientcapillary extraction.
The correct temperature regime must be used in order to achieve debinding. A slow heating
rate must be applied in order to give the wicking agent time for extraction. Typical
debinding cycles last from 20 hours to several days.
The adhered wicking agent causes problems, because it would lead to a rough surface after
the sintering. Therefore, it should be thoroughly cleaned from the debinded parts.
Fig. 9. Alumina wicking agent in the granular form. Photograph a), taken with optical
microscop, shows granules of the wicking agent. Photograph b), taken with scanning
electrone microscope show the surface of one granule. It can be seen, that the granula
contains very fine porosity, which is a condition for efficient capillary extraction.
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Wick Debinding – An Effective Wayof Solving Problems in the Debinding Process of Powder Injection Molding 101
Fig. 10. Comparison of the properly debinded part (left) with the deformed part (right),which was deformed and had granulate wicking agent adhered to the surface. The defectwas caused when the part was embedded into a too hot wicking agent, which had not beencooled enough after a thermal regeneration.
Fig. 11. Wick-debinded parts are loaded on a tray for the sintering process. Successfullywick-debinded samples contain an open porosity and are ready for a fast sintering cycle, inwhich complete burnout of the residual binder takes place.
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Some Critical Issues for Injection Molding102
After single or multiple uses the wicking agent accumulates a certain amount of organicphase – binder degradation products. This phase decreases the porosity of the wicking agentand thus its capillary-extraction ability. However, it can be regenerated by heating it toaround 600°C, where all the organics burn. In practice, a wicking granulate with different
amounts of residual organic phase can be used for debinding different parts. Small parts aredebinded in the embedment, which is rich in organics, whereas the large parts are debindedusing freshly regenerated granulate with a maximum capillary-extraction ability. As aresult, the embedment can thus be consequently used for ever smaller parts.
5. Conclusion
Removing the organic binder from the powder-injection-molded parts with the use ofhighly a porous granular embedment has been shown to be an effective method. It offersmany benefits, such as shorter debinding time due to capillary extraction. Also, itguarantees a gentle physical support for the parts and therefore reduces certain flaws, such
as distortion and cracking. Wick-debinding also has an important drawback, such as thepractical problems of cleaning the debinded bodies. These drawbacks are the reason, thatwick debinding is avoided if possible. In the case of high pressure injection molding it ispossible to avoid using the wick embedment because of the use of high melting pointpolymeric binders in addition to the low melting point wax.
However in the case of low-pressure-injection molding, where the debinding process is evenmore delicate the use of wick-debinding has a firm place. Furthemore, future improvementsin wick-debinding and the developments of novel procedures can make this highly effectiveway of removing the binder from injection-molded parts easier to apply and morepopularize in the industry.
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Some Critical Issues for Injection Molding
Edited by Dr. Jian Wang
ISBN 978-953-51-0297-7
Hard cover, 270 pages
Publisher InTech
Published online 23, March, 2012
Published in print edition March, 2012
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This book is composed of different chapters which are related to the subject of injection molding and written by
leading international academic experts in the field. It contains introduction on polymer PVT measurements and
two main application areas of polymer PVT data in injection molding, optimization for injection molding
process, Powder Injection Molding which comprises Ceramic Injection Molding and Metal Injection Molding,
ans some special techniques or applications in injection molding. It provides some clear presentation of
injection molding process and equipment to direct people in plastics manufacturing to solve problems and
avoid costly errors. With useful, fundamental information for knowing and optimizing the injection molding
operation, the readers could gain some working knowledge of the injection molding.
How to reference
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molding/wick-debinding-an-effective-way-of-solving-problems-in-the-debinding-process